There are those that are highly intelligent people and there are those that are not. My question is...?

Great question! I suppose firstly it depends on what you're measuring intelligence on. I think in Western culture we tend to determine intelligence by school grades and what is the highest mark one can achieve in an exam. There is also IQ, but for me personally intelligence is based on intuition, quick-thinking and an all-round education. Having said that, expertise in any field should also, I feel, be classed as intelligence. I suppose overall I think intelligence is just deep knowledge, which generally comes from:

Reading

Paying attention in school (as well as the opportunity to go to school in the first place)

Hard work

Experience

Sensitivity and intuition

Conversations and debates with 'intelligent' people

'Not so intelligent' is caused by a lack of education, either from a lack of opportunity, or possibly even just a lack of effort. A person might have the opportunity to become intelligent and learn, but if they don't put any effort in then they will not improve. There are also certain biological factors. I personally struggle with the sciences. Although I have a great interest in biology and chemistry, I just can't remember scientific facts or terminology. Now obviously if I worked extremely hard, and did so often, I'm sure this would improve. However, I don't have a natural ability for it, and I feel this prevents me somewhat from being called intelligent from a purely scientific point of view.

Intelligence must also be judged in context, in particular, age. You might say that a 10 year old is not intelligent compared to Hawking or Shakespeare, but they are top of their class and are thus intelligent for their age.

One should also be able to have an intelligent conversation in order to be deemed intelligent I would argue. For example, perhaps debating about current topics - like genetic engineering, politics, feminism, and so on. However, I feel that a person should not have to have a deep knowledge of a topic in order to debate it in a casual manner, obviously it helps, but it should not be vital. I suppose I am saying that having a well-thought-out opinion also counts towards intelligence.

Essentially, intelligence is a lifelong journey of improvement - you do indeed learn something new every day and as you get older, you get wiser, which also contributes to intelligence. There are certain people, unfortunately, who are so self-obsessed that they do not progress, as they notice very little around them, and thus do not use their experiences in any meaningful way.

I hope this answers your question! This is all just what I believe.